The proportion of adults in the US who own an e-reader has doubled in the last six months while tablet ownership hasn't risen as sharply in the same period.

These findings come from Pew's latest report on its Internet & American Life Project and are from a survey conducted between April 26 and May 22, 2011 of 2,277 adults ages 18 and older in the U.S by phone interviews conducted in English and Spanish.

The title page line,

Adoption rate of e-readers surges ahead of tablet computers

is perhaps an overstatement when you look into the figures.

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This graph does show a steeper growth for e-readers and going from 6% to 12% is a doubling, but tablets also went from 5% to 8% which is also pretty impressive growth.

Looking at the demographics is also interesting. Hispanic adults, college graduates and those living in households with incomes of at least $75,000 are most likely to own e-book readers.Parents are also more likely than non-parents to own these devices.

There was considerable growth in e-reader ownership between November 2010 and May 2011 among college graduates, one-fifth of whom now own these devices. Another change is that while in November  2010, parents and non-parents were equally likely to own e-readers the past six months ownership of these devices among parents has grown more rapidly than among-non-parents. Similarly, e-reader ownership grew at a faster pace among Hispanic adults over that time period than it did among white or African-American adults.

Overall, the highest rates of tablet ownership are among Hispanic adults and those with household incomes of at least $75,000 annually and between November 2010 and May 2011, the largest increases in tablet ownership have been among men when compared with women; Hispanic adults when compared with white and African-American adults; adults 18-29; those with some college or college degrees; and those reporting household incomes of $30,000 or more.

Other survey findings are that both e-reader and tablet ownership lag far behind other devices and that the cell-phone is by far the most popular with 83% of adults owning one:

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There is an overlap between ownership of e-readers and tablets with 3% of those surveyed owning both:

Pew's research doesn't comment on factors that might account for the spurt in growth of e-readers not being paralleled by tablets but there are some obvious ones.

Given the large proportion of adults that own a smartphone that overlaps in function with both an e-reader and a tablet consumers may not feel an urgent need to buy one of these two devices.

New and cheaper models of the Kindle that were launched in the six month period could account for the growth spurt noted.

The new crop of Honeycomb tablets with enhanced capabilities have yet to appear, coupled with the  Motorola Xoom not being competitive in terms of price, may be influencing potential buyers to wait for a few more months. 

More information

E-reader Ownership Doubles in Six Months